This invention relates to compositions for a zinc electrode suitable for use, e.g. in an accumulator of the nickel-zinc, silver-zinc or zinc-air type having an alkaline electrolyte.
A common drawback of existing zinc electrodes for such applications is their low life time, caused principally by the behavior of the composition of the electrode in the alkaline electrolyte. Such behavior involves the changes of concentration of hydroxyl and zincate ions in the electrolyte during charge and discharge, via the following equation: EQU Zn + 4 OH.sup.- .revreaction. Zn [(OH).sub.4.sup.2 ].sup.2.sup.- + 2e
Thus, during the discharging process, soluble zinc compounds are produced in the electrolyte, while during charging zinc is redeposited on the electrode collector. Unfortunately, the redeposition does not take place on those portions of the electrode from which the zinc entered the solution. This leads to an undesirable shifting of the active material on the collector, as well as to the formation of dendrites and to an accelerated consumption of the electrode.
While certain techniques exist to reduce these effects (e.g. electrolyte selection, addition of separators, etc.), their efficacy for the intended purpose is relatively limited.